Chapter
Four
Neuroscience
‘top-down’ connections, the story is quite different. This comes close to a dynam-
ical systems theory, to which we will return in the next chapter.
The research on binocular rivalry tells us many interesting things, and ties into
major current debates on brain function and structure. But serious problems
remain. First, these results provide only correlations, with all the ambiguity we
have seen that term to entail. Kanwisher (2001) has suggested that factors includ-
ing the strength of neural activation and connectivity between neural represen-
tations and other parts of the brain may be important in providing the added
extra that distinguishes mere necessary conditions from stronger sufficient con-
ditions for consciousness. Some first steps have been taken towards establishing
causal connections too, however. For example, Afraz, Kiani, and Esteky (2006)
trained monkeys to categorise images as ‘face’ or ‘non-face’ and then stimulated
clusters of neurons in the ventral stream while they looked at ambiguous images.
The monkeys were more likely to indicate ‘face’ when face areas were activated,
suggesting that these areas play a causal role in the act of recognition as well as
merely correlating with it. They also found effects of degree of face selectivity
and neuronal cluster size in the stimulated sites, and effects of the precise tim-
ing of the stimulation. Similar research with humans has found that stimulation
of face-selective areas in right fusiform gyrus causes changes in the conscious
perception of faces, whereas stimulation of the left fusiform gyrus causes non-
face-related visual changes (Rangarajan et al., 2014).
Even when causal links between brain activity and conscious experience are
demonstrated, however, they still do not touch the central mystery or help to
remove the magic from the ‘magic difference’. They do not explain how conscious-
ness could be ‘generated’ in one place rather than another, how it could ‘arise’ at
one level of processing and not another, or what it means for some processes to
be ‘qualia-laden’ while others are not.
A possibility worth considering is that the whole enterprise is misconceived. For
example, if vision is a grand illusion, then there is no ‘vivid representation in our
brains of the scene directly before us’ (Crick, 1994, p. 207). So looking for its neural
correlates is doomed to failure (Blackmore, 2002). If we challenge some of the
other common metaphors of neuroscience, we might come to the same conclu-
sion: maybe we should call off the search for the correlates of the ‘contents of
consciousness’, because consciousness is not a container.
A different way of interpreting the same data is to imagine that the quality of any
experience depends on multiple processes and brain areas. Perhaps a complete
integrated system is needed to have the kind of complex, personal, reportable
experiences we usually call ‘conscious’. This might be in the form of a ‘dynamical
brain signature’ (Lutz et al., 2002) or a certain amount of ‘integrated information’
in the physical (neural) system (Tononi, 2004; see also Chapter 5). Some, like Andy
Clark, Alva Noë, and Francisco Varela, would go further and say that a complex
environment or world is needed as well as a whole body and brain. In this case the
findings are still fascinating in telling us which brain areas are necessary and/or suf-
ficient for reportable experiences, but they need not indicate that there is a neural
location of awareness or that some brain areas ‘generate qualia’ while others do not.
Maybe we need to make our methods of inquiry even more interdisciplinary to do
justice to all these interconnections far beyond the brain, including how they vary
from person to person. We will explore this idea in detail in Chapter 17, considering
‘there seems to be
a magic difference
between conscious and
unconscious processes’(Blackmore, 2012)